Coaster sleds have been popular for many years. The most popular form of such sleds comprises a pair of longitudinally-extending and laterally-spaced runners, connected to each other by two or more lateral struts. Slats extend longitudinally over the struts between the runners for supporting a rider in either a prone or sitting position. The runners have front ends which bow upwardly. A lateral steering handle is operatively connected to the front ends of the runners. The steering handle can be turned to arc the runners and to thereby curve the path of the sled. In most embodiments of such sleds, the steering handle is mounted to a steering link which extends longitudinally from the front end of a center rider support slat to a forward cross-piece between the front ends of the respective runners. Turning the steering handle turns the steering link and thereby laterally displaces the cross-piece and the connected front ends of the runners. This produces an arc along forward portions of the runners, thereby curving the path of the sled.
In most sleds of this design, the mounting of the slats to the struts is such that it allows the runners to arc along their entire lengths. The overall design is intended to produce an arc along the entire lengths of the runners when the steering handle is turned. In spite of this, it is often very difficult to make sharp turns with a coaster sled of this design. This is at least partially due to the fact that displacing force is applied when turning the steering handle only at the extreme front ends of the sled runners.
The prior art includes variations of the designs described above. Refer, for instance, to U.S. Pat. No. 1,298,355 to Knudsen, dated Mar. 25, 1919. The Knudsen patent discloses a runner sled similar in design to that described above except for the steering mechanism. Rather than displacing the front ends of the runners, cables run from a steering wheel to an intermediate portion of the runners. Turning the steering wheel produces a lateral displacement of an intermediate portion of the runners.
Even if this prior art design or another prior art design could be utilized to achieve greater arcing of sled runners, lateral stability would likely remain as a problem. Sharp cornering tends to shift a rider's weight to the outside and to either tip the sled over to throw the rider from the sled. Riders often lean over the inside edge of a sled to counteract this tendency, even though this frequently results in dragging arms or legs.
The invention described below greatly improves the cornering characteristics of flexible rail coasters or sleds, and also increases the speed which can be attained with such vehicles. This is accomplished while retaining, for the most part, the traditional construction and characteristics of flexible runner vehicles.